OK, let's do this. We've got 2220 and 6125 and we're adding them all together.

Step 1: We'll start by adding the digits 0 & 5 in column 1 and get 5.

Step 2: We'll start by adding the digits 2 & 2 in column 2 and get 4.

Step 3: We'll start by adding the digits 2 & 1 in column 3 and get 3.

Step 4: We'll start by adding the digits 2 & 6 in column 4 and get 8.

So, 2220 + 6125 = 8345.

